Abstract: The amount of memory required for CCLM prediction is reduced. The CCLM prediction parameter derivation unit (310442) derives a scale shift value corresponding to a luma difference value, and derives a CCLM prediction parameter, by shifting, by using the scale shift value, a value obtained by multiplying a value of a table referred to with a value obtained by performing right shift of the luma difference value by the scale shift value as an index and a chroma difference value. In addition, in a case of deriving a prediction image, a bit width is reduced by adaptively deriving a shift amount of a linear prediction parameter from the chroma difference value.

Abstract: An image decoding device (31) includes a transform coefficient decoding unit (311) configured to decode a transform coefficient for a transform tree included in a coding unit. In the transform tree, the transform coefficient decoding unit splits a transform unit corresponding to luminance and then decodes the transform coefficient related to the luminance, and does not split the transform unit corresponding to chrominance and decodes the transform coefficient related to the chrominance.

Abstract: A method for signaling gradual refresh for encoding a set of pictures performed by an electronic device is provided. The method identifies a first picture in the set of pictures as being associated with a gradual refreshed picture, and stores a network abstraction layer (NAL) unit type in a coded stream associated with the first picture. The NAL unit type identifies a presence of the gradual refreshed picture. The method then stores, in the coded stream, an enable flag to identify a use of the gradual refresh for encoding at least a subset of pictures in the set of pictures.

Abstract: An image decoding apparatus including a header decoder configured to decode, from coded data, a flag indicating whether dependent quantization is enabled and a flag prohibiting transform skip residual quantization, and a TU decoder configured to decode a transform coefficient in a TU block in an RRC mode in which a LAST position is coded, the LAST position corresponding to a decoding start position for the transform coefficient, or a TSRC mode in which the LAST position is not coded. The TU decoder performs dependent quantization in the RRC mode in a case that the transform coefficient for transform skip is decoded in the TSRC mode, and does not perform dependent quantization in the RRC mode in a case that the transform coefficient for transform skip is decoded in the RRC mode.

Abstract: The mere use of supplemental enhancement information of a deep learning post-filter degrades the performance of improving image quality because filter strength fails to be adjusted in a case that features of an image vary with frame. Solution Provided is a 3D data decoding apparatus for decoding coded data into 3D data including location information and attribute information, the decoding apparatus including a header decoder configured to decode the coded data into supplemental enhancement information of a deep learning post-filter, an attribute image decoder configured to decode the coded data into an attribute image, and an attribute image filter unit configured to perform filtering processing on the attribute image, wherein the header decoder performs decoding into purpose information indicating that the attribute image filter unit performs the filtering processing on the attribute image.

Abstract: Provided are an image decoding apparatus (31) and an image coding apparatus (11) in which both transform precision and residual coding efficiency are preferable. Included are a TU decoder (3024) configured to decode, from coded data, a syntax element representing an absolute value of a transform coefficient, a scaling unit (311) configured to multiply a transform coefficient by a quantization-parameter dependent value and perform right-shift by a first shift value, and to perform clipping using a minimum value and a maximum value according to a first range, and an inverse conversion processing unit (311) configured to convert a scaled transform coefficient, perform clipping using the minimum value and the maximum value according to the first range to derive an intermediate coefficient, further transform an intermediate variable, and perform right-shift by a second shift value.

Abstract: Object Known derivation, on a per intra prediction modes basis, of a template-based intra mode derivation based on a difference between a template prediction image and a template image has a problem that derivation of the template image and cost calculation require great computational resources. Solution Included are an intra prediction image generation unit configured to generate a template prediction image for an intra prediction mode candidate predetermined, a template cost derivation unit configured to derive a cost from the template prediction image and a template image corresponding to an image near a target block, and an intra prediction image generation unit configured to generate an intra prediction image by using a selected intra prediction mode, wherein the number of taps of an interpolation filter for the template prediction image is less than the number of taps of an interpolation filter for intra prediction.

Abstract: Object Known derivation, in units of intra prediction modes, of a template-based intra prediction mode based on a difference between a template prediction image and a template image has a problem that derivation of the template image and cost calculation require great computational resources. Solution An image decoding apparatus includes an intra prediction image generation unit configured to generate a template prediction image for a prescribed intra prediction mode candidate, a template cost derivation unit configured to derive a cost from the template prediction image and a template image corresponding to an image near a target block, and an intra prediction image generation unit configured to generate an intra prediction image by using a selected intra prediction mode, and a reference sample is sampled that is used to generate the template prediction image.

Abstract: Object In the existing specifications for neural network post-filter characteristics SEI, in order to perform post-filtering processing, the SEI needs to be transmitted for each picture, which presents a problem of redundancy in a case that the same post-filtering processing is performed in all of pictures. Solution A video decoding apparatus according to an aspect of the present invention includes an image decoding apparatus configured to decode coded data and generate a decoded image, an inverse conversion information decoding apparatus configured to decode inverse conversion information as supplemental enhancement information on a per sequence basis, and a resolution inverse conversion apparatus configured to conversion the decoded image to an image with an indicated resolution by using the inverse conversion information, the resolution inverse conversion apparatus using a neural network.

Abstract: Object A video coding and decoding apparatus that can enhance coding efficiency is provided. Solution A video decoding apparatus includes an OOB determination unit configured to determine whether a reference block is a target of OOB processing by comparing coordinates of the reference block with coordinates of a picture, and an OOB mask derivation unit configured to derive mask data indicating whether a pixel is available by comparing coordinates of the pixel included in the reference block with the coordinates of the picture. The OOB determination unit determines whether the reference block is the target of the OOB processing based on presence or absence of processing to be applied to a reference picture including the reference block.

Abstract: In a case that luminance information is used for a chrominance prediction in a separate coding tree structure, there is a problem that chrominance blocks cannot be decoded before all luminance blocks constituting a tree are decoded. An image decoding apparatus that splits an image into coding tree units (CTUs) that are rectangular for processing includes a CT information decoding unit configured to split a CTU of the CTUs into coding trees CTs and to process one or more color components as a single coding tree using one coding tree CT of the coding trees CTs or process two or more color components as a separate coding tree using two or more coding trees CTs of the coding trees CTs depending on a tree mode, a CU decoding unit configured to decode a split flag indicating whether to further split a CT of the CTs and to recursively perform block splitting, and an intra predictor configured to use a decoded image of one color component to generate a prediction image of another color component.

Abstract: A device is provided with: a first transformer which transforms an coding unit (CU); and a second transformer which transforms a part of first transform coefficients output from the first transformer, wherein the second transformer transforms at least any of the first transform coefficients for a region (first region) having different sizes in a horizontal direction and a vertical direction or the first transform coefficients for a non-rectangular region (second region).

Abstract: Object To reduce distortion caused by coding a mesh displacement image, and code and decode 3D data with high quality in coding and decoding 3D data using video coding scheme. Solution A 3D data decoding apparatus for decoding 3D coded data includes an image decoder configured to decode the 3D coded data into a mesh displacement image, a displacement unmapping unit configured to generate a mesh displacement from the mesh displacement image, and a coordinate system conversion unit configured to perform conversion of a coordinate system of the mesh displacement.

Abstract: A mechanism is provided that implements video coding and decoding such that only a specific partial image region on a screen can be independently decoded. A video decoding apparatus (31) according to an aspect of the present invention configures, in intra prediction, inter prediction, loop filter processing, or the like, a partial image region in a picture, handles a region outside the partial image region in a similar manner to a region outside the picture, and does not apply such restriction to a non-partial image region other than the partial image region in the picture.

Abstract: Provided is a video decoding apparatus for decoding coded data of a tile group in which a picture is split into rectangular regions, the tile group being composed of segments, the video decoding apparatus including: a header decoder configured to decode the number of tiles, a WPP enabled flag, and a slice enabled flag indicating whether segments in a target tile group are rectangular tiles, CTU rows, or slices from a tile group header, wherein the header decoder is configured to decode only one of the number of tiles being two or more, the WPP enabled flag being 1, and the slice enabled flag being 1 in one tile group.

Abstract: A video decoding apparatus includes matrix reference pixel derivation circuitry that derives reference samples by using top neighboring samples and left neighboring samples of a current block, weight matrix derivation circuitry that derives a weight matrix, matrix prediction image derivation circuitry that derives a prediction image, and matrix prediction image interpolation circuitry that derives a predicted image by using the prediction image. A size index is derived according to a value of a target block width and a value of a target block height. A prediction size is derived using the size index. In a case that a first condition, that both the value of the transform block width and the value of the transform block height are equal to 4, is true, the size index is set equal to 0 and the prediction size is set equal to 4.

Abstract: A device is provided with: a first transformer which transforms an coding unit (CU); and a second transformer which transforms a part of first transform coefficients output from the first transformer, wherein the second transformer transforms at least any of the first transform coefficients for a region (first region) having different sizes in a horizontal direction and a vertical direction or the first transform coefficients for a non-rectangular region (second region).

Abstract: A video decoding apparatus includes an image decoding apparatus configured to decode coded data to generate a decoded image, and a resolution inverse conversion apparatus configured to convert a resolution of the decoded image to a specified resolution by using inverse conversion information. The resolution inverse conversion apparatus uses a neural network. In the resolution inverse conversion apparatus, information, indicating a number of horizontal pixels and a number of vertical pixels of a patch size being a unit of processing of the neural network, is decoded. The number of horizontal pixels and the number of vertical pixels of the decoded image are set equal to a maximum value of the number of horizontal pixels and a maximum value of the number of vertical pixels of the patch size, respectively.

Abstract: A moving image decoding method for generating prediction images by a device is provided. First and second prediction image are generated. Bidirectional prediction gradient change prediction processing is performed by using a first shift value and difference values of horizontally neighboring samples and vertically neighboring samples in the first and second prediction images to generate a first, second, third and fourth gradient images. Motion information is derived by using the first and second prediction images, the first, second, third and fourth gradient images, a second shift value, and a third shift value. Motion compensation correction value is derived by using the motion information and the first, second, third and the fourth gradient images. The third prediction image is generated by using the first and second prediction images and the motion compensation correction value. The first, second and third shift values are derived based on a pixel bit length of eight.

Abstract: Provided is a video decoding apparatus for decoding coded data of a tile group in which a picture is split into rectangular regions, the tile group being composed of segments, the video decoding apparatus including: a header decoder configured to decode the number of tiles, a WPP enabled flag, and a slice enabled flag indicating whether segments in a target tile group are rectangular tiles, CTU rows, or slices from a tile group header, wherein the header decoder is configured to decode only one of the number of tiles being two or more, the WPP enabled flag being 1, and the slice enabled flag being 1 in one tile group.